Episode 41 is all about Stegoceras, a pachycephalosaurid with a clean domed head.
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On this episode, we focus on:
- The dinosaur of the day: Stegoceras, whose title means “horned roof”
- Pachycephalosaurid dinosaur that lived in North America through the Late Cretaceous
- First named in 1902, by Lawrence Lambe
- Bones first present in 1889
- When Stegoceras was first discovered, scientists thought the bones had been stomach ribs, which aren’t present in different ornithischians (however now regarded as ossified tendons
- Kind species is Stegoceras validum (based mostly on 40 specimens discovered within the Stomach River Group of Alberta, Canada)
- Between the Twenties to 1945, Stegoceras was regarded as Troodon, as a result of that they had comparable tooth (however then higher specimens had been discovered)
- Was extra Stegoceras species, resembling Stegoceras lambei, Stegoceras sternbergi, and Stegoceras breve, however had been later assigned to different genera
- In 1983 Stegoceras browni was renamed Ornatotholus, however is now thought-about to be a juvenile of S. validum
- One genus, Ornatotholus, is regarded as a juvenile Stegoceras validum, based mostly on an evaluation of the cranial dome ontogeny
- 2011 PLOS ONE Cranial Ontogeny in Stegoceras validum (Dinosauria: Pachycephalosauria): A Quantitative Mannequin of Pachycephalosaur Dome Development and Variation”: research that exhibits the cranium modified with age and Ornatotholus browni is a juvenile of S. validium
- In 1990, Mark Goodwin described the cranium of an grownup Stegoceras, however the cranium was massive for a Stegoceras. In 2003, Robert Sullivan wrote a evaluate of the fossils discovered, and thought it was distinct sufficient to be named Hanssuesia sternbergi. However a more moderen research by Ryan Schott and David Evans argues the cranium is an grownup Stegoceras, although it lacked nodes at the back of the cranium which is seen on youthful Stegoceras (undecided why it doesn’t have the nodes, attainable they only modified with age)
- In 2011, a brand new legitimate species was named by Steven E. Jasinski and Robert M. Sullivan, known as Stegoceras novomexicanum, based mostly on two partial skulls
- Stegoceras novomexicanum was solely about 4 toes lengthy, in comparison with S. valdium which was over 6 toes lengthy
- Stegoceras is a extra widespread, higher recognized pachycephalosaur
- A part of the group Marginocephalia and Pachycephalosauria
- Most likely developed from Hypsilophodon (from episode 28)
- Bones have been present in Alberta Canada and New Mexico
- About 6.6 ft (2 m) lengthy and weighed 22-88 lb (10-40 kg)
- About 4 ft or 1.2 m tall
- Bipedal
- Could have gone on all 4 toes to search for vegetation to eat
- Had small tooth that had been curved, with serrated edges (once more, much like Troodon)
- Had legs thrice longer than arms
- Had an S- or U-shaped neck
- Stegoceras had spherical ahead dealing with eye sockets, so most likely had good imaginative and prescient and binocular imaginative and prescient
- Most likely a herding dinosaur
- Different dinosaurs that lived by Stegoceras had been Albertosaurus, Maiasaura, T-rex, Ankylosaurus, Parasaurolophus, Corythosaurus and Dryptosaurus
- Had a big mind that was in a thick dome about 3 in or 7.5 cm thick (and divided into two components)
- The dome was clean
- Males had thicker domes than females (so did older Stegoceras)
- In 1981 the Journal of Paleontology revealed “A Morphometric Examine of the Carnium of the Pachycephalosaurid Dinosaur Stegoceras” which measured the braincases of 29 specimens and located that what was as soon as regarded as two kinds of Stegoceras was simply female and male (males had thicker domes than females)
- Scientists initially thought male Stegoceras rammed their heads collectively (like bighorn sheep or musk oxen), however in 1997 some paleontologists stated the dome was not massive sufficient for that sort of impression, and wouldn’t have labored until the heads hit at simply the precise spot; additionally, their head, neck and physique would have needed to be in a horizontal line to transmit stress, however scientists suppose their necks had been S- or U-shaped; an alternate is flank-butting, which includes transferring the neck and rotating the top and never severely injure the opponent (bone rim above the attention might have protected its eyes)
- Mark Goodwin from College of California Berkeley analyzed pachycephalosaur skulls and located no proof of healed scars, and located hat the cranium bone is porous and fragile beneath stress, so they might have killed one another in fights
- In 2011 Eric Snively and Theodor analyzed CT scans of Stegoceras validum skulls, and located they may have head-butted, based mostly on an additional layer of dense bone in the course of the dome, which might have been further safety
- Eric Snively and researched revealed a research in 2011 in PLOS One known as”Frequent Purposeful Correlates of Head-Strike Conduct within the Pachycephalosaur Stegoceras validum (Ornithischia, Dinosauria) and Combative Artiodactyls” that confirmed Stegoceras may have head butted
- They did CT scans on fashionable animal skulls and Stegoceras, then made a digital simulation exhibiting beasts going face to face
- Discovered its mind was extra protected than bighorn sheep and musk ox
- Stegoceras had an additional layer of dense bone in the course of its dome, along with a stiff rind exterior with spongy materials that may soak up vitality (and hold them acutely aware when butting heads)
- Eric Snively stated there are “alternating layers of stiff and compliant bone within the domes…virtually as if they’re carrying a double bike helmet”
- Could have butted heads to draw mates
- The research of Stegoceras that discovered the domes may dissipate impression forces doesn’t show they rammed heads, they might have flanked one another by swinging their heads into every others sides as an alternative
- Stegoceras was a heavy breather
- In 2014 Anatomical Report revealed Jason Bourke and his staff’s research that confirmed Stegoceras cooled its mind by respiration
- It breathed like a chook or reptile and took lengthy, deep breaths, based mostly on a CT scan by Jason Bourke and colleagues (respiration helped cool its mind by cooling blood vessels within the mind; additionally might haven’t had nostril hairs like fashionable reptiles so would have had a lot of mucous to keep away from inhaling small, airborne objects
- Dinosaurs didn’t have nostril hairs (wanted mucous)
- Bourke and colleagues scanned the Stegoceras cranium and located the turbinates
- Jason Bourke from the College of Ohio discovered that Stegoceras had turbinates, intricate buildings of their nostril, to assist cool blood and stop water loss
- They ran digital air by means of a 3D mannequin of the dinosaur’s nostril to see how the turbinates altered airflow
- That’s how they discovered it acted as a cooling system, the place the air breathed in cooled the nice and cozy blood inside earlier than flowing to the mind (helped them hold cool when operating away from predators)
- As a result of dinosaurs had been so massive, overheating was a serious challenge
- Stegoceras is a comparatively small dinosaur, however nonetheless cooled its mind
- Had a superb sense of scent, to smell out predators, mates, and meals
- Marginocephalia (“fringed heads”) is a clade of ornithiscians that had been herbivores (each bipedal and quadrupedal), with bony ridges of frills in the back of the cranium; lived in Jurassic and Cretaceous
- Pachycephalosauria (“thick headed lizards”) can be a clade of ornithiscians; lived within the late Cretaceous in North America and Asia
- Pachycephalosaurs had been herbivores with thick skulls
- They had been all bipedal
- Had thick skulls
- Some had domed skulls, others flat or wedge formed
- Enjoyable Truth: The phaeomelanosomes that probably saved pigments in dinosaurs’ pink feathers is similar because the pigment that makes Garret’s hair pink!